1 // SPDX-License-Identifier: GPL-2.0-or-later 2 /* 3 * Crypto library utility functions 4 * 5 * Copyright (c) 2006 Herbert Xu <herbert@gondor.apana.org.au> 6 */ 7 8 #include <asm/unaligned.h> 9 #include <crypto/algapi.h> 10 #include <linux/module.h> 11 12 /* 13 * XOR @len bytes from @src1 and @src2 together, writing the result to @dst 14 * (which may alias one of the sources). Don't call this directly; call 15 * crypto_xor() or crypto_xor_cpy() instead. 16 */ 17 void __crypto_xor(u8 *dst, const u8 *src1, const u8 *src2, unsigned int len) 18 { 19 int relalign = 0; 20 21 if (!IS_ENABLED(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS)) { 22 int size = sizeof(unsigned long); 23 int d = (((unsigned long)dst ^ (unsigned long)src1) | 24 ((unsigned long)dst ^ (unsigned long)src2)) & 25 (size - 1); 26 27 relalign = d ? 1 << __ffs(d) : size; 28 29 /* 30 * If we care about alignment, process as many bytes as 31 * needed to advance dst and src to values whose alignments 32 * equal their relative alignment. This will allow us to 33 * process the remainder of the input using optimal strides. 34 */ 35 while (((unsigned long)dst & (relalign - 1)) && len > 0) { 36 *dst++ = *src1++ ^ *src2++; 37 len--; 38 } 39 } 40 41 while (IS_ENABLED(CONFIG_64BIT) && len >= 8 && !(relalign & 7)) { 42 if (IS_ENABLED(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS)) { 43 u64 l = get_unaligned((u64 *)src1) ^ 44 get_unaligned((u64 *)src2); 45 put_unaligned(l, (u64 *)dst); 46 } else { 47 *(u64 *)dst = *(u64 *)src1 ^ *(u64 *)src2; 48 } 49 dst += 8; 50 src1 += 8; 51 src2 += 8; 52 len -= 8; 53 } 54 55 while (len >= 4 && !(relalign & 3)) { 56 if (IS_ENABLED(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS)) { 57 u32 l = get_unaligned((u32 *)src1) ^ 58 get_unaligned((u32 *)src2); 59 put_unaligned(l, (u32 *)dst); 60 } else { 61 *(u32 *)dst = *(u32 *)src1 ^ *(u32 *)src2; 62 } 63 dst += 4; 64 src1 += 4; 65 src2 += 4; 66 len -= 4; 67 } 68 69 while (len >= 2 && !(relalign & 1)) { 70 if (IS_ENABLED(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS)) { 71 u16 l = get_unaligned((u16 *)src1) ^ 72 get_unaligned((u16 *)src2); 73 put_unaligned(l, (u16 *)dst); 74 } else { 75 *(u16 *)dst = *(u16 *)src1 ^ *(u16 *)src2; 76 } 77 dst += 2; 78 src1 += 2; 79 src2 += 2; 80 len -= 2; 81 } 82 83 while (len--) 84 *dst++ = *src1++ ^ *src2++; 85 } 86 EXPORT_SYMBOL_GPL(__crypto_xor); 87 88 MODULE_LICENSE("GPL"); 89